For people who have to use their laptops on the go a lot it is useful because you are not constrained by local wi-fi networks which are generally unsecured and often have use fees attached. A mobile hotspot allows you to run your computer off a mobile hotspot device that ties in with the wireless cell-phone networks. The new smartphones generally have the ability to act as mobile hotspots, but it does have another charge per month. I know I can get it for my Droid through Verizon for another $30/mo.